diff --git a/Project.toml b/Project.toml
index 3dfff5e8..fe49d50e 100644
--- a/Project.toml
+++ b/Project.toml
@@ -8,6 +8,7 @@ BinaryProvider = "b99e7846-7c00-51b0-8f62-c81ae34c0232"
 GAP = "c863536a-3901-11e9-33e7-d5cd0df7b904"
 Singular = "bcd08a7b-43d2-5ff7-b6d4-c458787f915c"
 lib4ti2_jll = "1493ae25-0f90-5c0e-a06c-8c5077d6d66f"
+cddlib_jll = "f07e07eb-5685-515a-97c8-3014f6152feb"
 Graphviz_jll = "3c863552-8265-54e4-a6dc-903eb78fde85"
 Pkg = "44cfe95a-1eb2-52ea-b672-e2afdf69b78f"
 Markdown = "d6f4376e-aef5-505a-96c1-9c027394607a"
diff --git a/deps/build.jl b/deps/build.jl
index 8ec7d9fa..d43e8db7 100644
--- a/deps/build.jl
+++ b/deps/build.jl
@@ -9,3 +9,5 @@ for pkg in PACKAGES_TO_COMPILE
     GAP.Packages.install(pkg)
 
 end
+
+CompileCddInterface()
diff --git a/deps/homalg-project.jl b/deps/homalg-project.jl
index 0ef40936..39ebdd99 100644
--- a/deps/homalg-project.jl
+++ b/deps/homalg-project.jl
@@ -120,6 +120,7 @@ global PACKAGES_BASED_ON_CAP = [
     "CategoryConstructor",
     "CategoriesWithAmbientObjects",
     "CatReps",
+    "CddInterface",
     "ComplexesCategories",
     "DerivedCategories",
     "FinSetsForCAP",
@@ -175,6 +176,8 @@ end
 
 export RemoveAllPackagesFromHomalgProject
 
+
+
 global PACKAGES_TO_COMPILE = [
     "Gauss",
     #"Browse", ## do not compile browse as it results into GAP raising the error "Error opening terminal: xterm-256color."
@@ -186,4 +189,52 @@ global PACKAGES_TO_COMPILE = [
     "orb",
 ]
 
-global PACKAGES_DOWNLOADING_EXTERNAL_CODE = ["CddInterface", "NormalizInterface"]
+import cddlib_jll
+
+function CompileCddInterface(; print_available = true, test_availability = true)
+    
+    name = "CddInterface"
+    
+    gstr = julia_to_gap( name )
+    
+    if ( test_availability == false ) || ( GAP.Globals.TestPackageAvailability( gstr ) == GAP.Globals.fail )
+        pkg = GAP.Globals.PackageInfo( gstr )
+        
+        if GAP.Globals.Length( pkg ) == 0
+            dirs = gap_to_julia(GAP.Globals.String( GAP.EvalString("List(DirectoriesLibrary(\"pkg\"), d -> Filename(d, \"\"))")))
+            @warn "unable to find package named \"" * name * "\" in " * dirs
+            return false
+        end
+        
+        pkg = pkg[1]
+        
+        path = gap_to_julia( pkg.InstallationPath )
+        
+        @info "Compiling \"" * path * "\""
+        
+        cd(path)
+        
+        run(`./autogen.sh`)
+        run(`./configure --with-gaproot=$(GAP.GAPROOT) --with-cddlib=$(cddlib_jll.artifact_dir)`)
+        
+        run(`make -k -j$(Sys.CPU_THREADS)`) ## -k = Keep going when some targets can't be made.
+        
+        if GAP.Globals.TestPackageAvailability( gstr ) == GAP.Globals.fail
+            @warn "Compiling the package \"" * name * "\" failed."
+            return false
+        end
+        
+        @info "Compiling the package \"" * name * "\" was successful."
+        return true
+        
+    end
+    
+    if print_available == true
+        @info "Package \"" * name * "\" is already installed."
+    end
+    
+    return true
+    
+end
+
+export CompileCddInterface
diff --git a/test/cddlib.jl b/test/cddlib.jl
new file mode 100644
index 00000000..a4d2e018
--- /dev/null
+++ b/test/cddlib.jl
@@ -0,0 +1,10 @@
+@testset "CddInterface" begin
+    LoadPackage("CddInterface")
+    C = cdd_PolyhedronByInequalities([ [ 0, 1, 0 ], [ 0, 1, -1 ] ])
+    rays = Cdd_GeneratingRays( C )
+    @test rays == cdd_prepare_gap_input(rays)
+    @test rays == GAP.Globals.List(
+        julia_to_gap([ [ 0, -1 ], [ 1, 1 ] ]),
+        julia_to_gap,
+    )
+end
diff --git a/test/runtests.jl b/test/runtests.jl
index a67a70fd..95e90f1c 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -5,6 +5,7 @@ DocMeta.setdocmeta!(HomalgProject, :DocTestSetup, :(using HomalgProject); recurs
 include("packages.jl")
 include("singular.jl")
 include("4ti2.jl")
+include("cddlib.jl")
 include("digraphs.jl")
 include("homalg_project.jl")
 include("testmanual.jl")